Conserving large predator populations is difficult due to the risk they pose to the health and safety of people and their livelihoods. Despite its challenges, it is important to get it right, as large predators often play a keystone role in ecosystems. Male saltwater crocodiles (SWC) (Crocodylus porosus) can reach lengths of 6-7 m and weigh up to 1,360 kg. Adult males usually measure between 4.3 and 5.2 m and weigh between 400 and 1000 kilograms, while female SWC attain a smaller size than males, often reaching a maximum length of 2.5 to 3 m (Kar and Bustrad, 1989; Webb et al., 2010; Basu et al., 2023). In India, they are found on the eastern coast and the Andaman Islands (ICEM, 2023).

Overexploitation, poaching, and uncontrolled hunting caused a major decline in the SWC population until the 1970s. In the late 1960s, SWC went extinct in Kerala, Tamil Nadu, and Andhra Pradesh states, while it remained in smaller numbers in Bhitarkanika and the Sundarbans (Amarasinghe et al., 2015; Basu et al., 2023; Samuel et al., 2025). In 1974, the United Nations Development Programme (UNDP) and the Food and Agriculture Organization (FAO), in partnership with the Government of India, initiated a SWC conservation program named ‘Baula’ in Bhitarkanika National Park (BNP) to conserve the estuarine SWC by establishing a captive breeding program at Dangamal with 95 sighting including 34 adults in 1976 (relative density = 0.87/km) (Kumar et al., 2012; Nayak et al., 2018; Patro and Padhi, 2019). In 2009, 1596 sightings (1484 individuals in the park (relative density = 13.5/km), and an additional 112 in the adjacent regions), the C. porosus population in BNP has been growing since the restoration effort began (Kar, 2009; Kumar et al., 2012). This has resulted in a rise in human-crocodile conflicts, notably in areas such as the BNP in India (Pattnaik et al., 2024; Than et al., 2024). This park holds approximately 74% of the Indian SWC (Webb et al., 2010). The BNP comprises 153 villages of Bhadrak and Kendrapara districts of Odisha, which fall under the eco-sensitive zone of the sanctuary (MoEFCC, 2022).

Human-wildlife conflict (HWC) is a persistent issue arising from the conflict between the requirements of wildlife and human beings, adversely impacting both (Mekonen, 2020; Lu and Huntsinger, 2023). It has also been shown that the social and ecological conditions in which interactions between people and animals take place affect the conservation efforts (Baynham-Herd et al., 2018). Like other crocodilians, C. porosus is an opportunistic feeder, using aggressive hunting or ‘sit and wait’ tactics (Webb and Messel, 1978; Amarasinghe et al., 2015). Conflicts between humans and SWC arise when their behavior or needs negatively impact people or when human activities adversely affect the wildlife (Kumar et al., 2012; ICEM, 2023). This is particularly clear as the populations of humans and SWC are expected to increase, with human activity impacting wildlife habitats. In some cases, wildlife populations are now recovering and re-entering areas they formerly occupied that are now occupied by humans (Patro and Padhi, 2019). Therefore, this study aims to examine the frequency of human and SWC conflicts adjacent to the BNP from January 2019 to January 2025. We further assessed the population of SWC in the BNP that changed over time and its association with the frequency of HWC. Furthermore, a key aspect of this study is the difficulty of recovering and conserving large predator populations due to the inherent risk they pose to people and their livelihoods. Moreover, in doing so, we hope to notify wildlife managers to create strategies to mitigate HWC conflicts while guaranteeing the sustainable conservation of crocodiles.

For this study, the primary data regarding the number of HWC from 2000 to 2025 was collected from the official records of the Mangrove Forest Division, Odisha, and from (Kar, and Nibas, 2024). Hatchlings (<0.6 m), yearlings (0.6-0.9 m), juveniles (0.9<1.8 m), adults, and subadults (>1.8 m) were categorized as per the data. Generalized Additive Models (GAMs) were constructed to account for the non-linear relationship between crocodile abundance and time. Only the total number of crocodiles, adult and sub-adult populations, were included in the analysis due to their involvement in attacks on humans. The model was demonstrated using the Mixed GAM Computation Vehicle with Automatic Smoothness Estimation (mgcv) package in R statistical software (Wood, 2017; R Core Team, 2021). Thin-plate regression splines smoothing was used by setting the default (k =10) in mgcv. Generalized Cross-Validation (GCV) was used as a smoothing parameter selection method. The fit of GAMs was checked using gratia package in R (Simpson, 2024).

Previously, the attack of this species around the BNP has been documented up to 2018 (Patro and Padhi, 2019; Khan et al., 2020). Incidents of fatal attacks on humans around the BNP area during the seven years (January 2019 to January 31^st, 2025) were collected from local and national news reports. The news search was conducted using the Google search engine and keywords such as “Crocodile attack in Kendrapara” or “Croc attack near Bhitarkanika” up to January 31^st, 2025. The primary data, like attack location, size of the SWC that attacks, activity done by the victim prior to the attack, month and year of the attack, were collected by visiting individual location and through field observations from local citizens of Kendrapara district, adjacent to the BNP in Odisha, India, up to January 31^st, 2025 by following (Khan et al., 2020). The obtained primary data was then verified by the forest official of the Mangrove Forest division, Odisha, to avoid duplication or any missing information during the study. The attacks were screened by following (Fukuda et al., 2014; Baker et al., 2024). The entire plot was generated using the ggplot2 package in the R programming language (Wickham et al., 2007).

The data suggested that, according to the annual census conducted by the Odisha Wildlife Organization, the SWC population in Bhitarkanika increased to 1826 in 2025, surpassing the count of 914 in 2000 ( Figure 1 ). The statistical analysis shows the total SWC population vs. year revealed a significant temporal trend (GAMs; EDF = 3.501, F = 121.4, R² = 0.991, GCV score: 1170.9), indicating that the number of SWC significantly increases (P < 0.001) over the years, approximately 36.4 individuals per year, which is a moderately complex to highly nonlinear trend. In adult (GAMs; EDF = 6.398, F = 68.66, R² = 0.958, GCV score: 179.94), a moderate nonlinear trend, and for sub-adult (GAMs; EDF = 6.909, F = 19.47, R² = 0.869, GCV score: 193.56), it is a highly complex, wiggly trend. Moreover, both populations revealed a significant increase (P < 0.001) over the years. The total summary of the GAMs is mentioned in ( Supplementary Table S1 ). The adult and sub-adult populations combinedly increase by 12.6 individuals per year ( Supplementary Figure S1 ).

During 2018-19 to 2024-25, a total of 14 geo-referenced sites were marked where attacks were recorded after verifying all occurrence sites ( Figure 2A ), and a total of 28 fatal attacks were recorded ( Figure 2B ). All the attacks occurred within 75 km upstream from the BNP, and victims were exposed to SWCs via activities such as bathing, washing, fishing, and grazing cattle, while the rest remained unclear ( Figure 2C ). The study also highlighted that all attacks were caused by the adult and sub-adult population of C. porosus of length (>1.8 m). The data also suggested that most attacks have been observed from June to October during the mating and nesting season of this species.